Das integrated digital off-air repeater

ABSTRACT

Embodiments may allow remote base transceiver stations (BTSs) physically located away from a local source of users to be able to provide local service as if the remote BTSs were at or near the local source of users. Some embodiments may include a plurality of BTSs, each having one or more sectors, and one or more digital access units (DAUs). Embodiments may also include a plurality of repeater digital units (RDUs), where each RDU may be configured to communicate to at least one of the plurality of BTSs and may be operable to route signals optically to the one or more DAUs. Embodiments may also include a plurality of digital remote units (DRUs) located at a location remote to the one or more DAUs, wherein the plurality of remote DRUs may be operable to transport signals to the one or more DAUs.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/743,789, filed on Jun. 18, 2015; which is a continuation of U.S.patent application Ser. No. 14/044,668, filed on Oct. 2, 2013, now U.S.Pat. No. 9,112,549, issued on Aug. 18, 2015; which claims priority toU.S. Provisional Patent Application No. 61/710,391, filed on Oct. 5,2012. The disclosures of each are hereby incorporated by reference intheir entirety for all purposes.

BACKGROUND OF THE INVENTION

Wireless and mobile network operators face the continuing challenge ofbuilding networks that effectively manage high data-traffic growthrates. Mobility and an increased level of multimedia content for endusers requires end-to-end network adaptations that support both newservices and the increased demand for broadband and flat-rate Internetaccess. One of the most difficult challenges faced by network operatorsis maximizing the capacity of their DAS networks while ensuringcost-effective DAS deployments and at the same time providing a veryhigh degree of DAS remote unit availability.

Despite the progress made in DAS networks, there is a need in the artfor improved methods and systems related to DAS networks.

SUMMARY OF THE INVENTION

The present invention generally relates to wireless communicationsystems employing Distributed Antenna Systems (DAS) as part of adistributed wireless network. More specifically, the present inventionrelates to a DAS utilizing a software configurable repeater digital unit(RDU). In a particular embodiment, the present invention has beenapplied to optically fed digital repeaters that can be configured in astar configuration or a daisy chained configuration. The methods andsystems described herein are applicable to a variety of communicationssystems including systems utilizing various communications standards.

Wireless and mobile network operators face the continuing challenge ofbuilding networks that effectively manage high data-traffic growthrates. Mobility and an increased level of multimedia content for endusers typically employs end-to-end network adaptations that support newservices and the increased demand for broadband and flat-rate Internetaccess.

A distributed antenna system (DAS) provides an efficient means ofutilization of base station resources. The base station or base stationsassociated with a DAS can be located in a central location and/orfacility commonly known as a base station hotel. The DAS networkcomprises one or more digital access units (DAUs) that function as theinterface between the base stations and the digital remote units (DRUs).The DAUs can be collocated with the base stations. Under certainembodiments the base station resources may not be collocated with theDAUs. Off-Air Repeaters can be used to relay remote BTS signals to oneor more DAUs. One or more Off-Air Repeaters can be used to communicatewith one or more base stations. The Off-Air Repeaters relay the RFsignals between the Donor BTS and coverage area.

Some embodiments may include a system for routing signals in aDistributed Antenna System (DAS). The system may include a plurality ofbase transceiver stations (BTS), each having one or more sectors, andone or more digital access units (DAUs). The system may also include aplurality of repeater digital units (RDUs), where each RDU may beconfigured to communicate to at least one of the plurality of BTSs andmay be operable to route signals optically to the one or more DAUs. Thesystem may also include a plurality of digital remote units (DRUs)located at a location remote to the one or more DAUs, wherein theplurality of remote DRUs may be operable to transport signals to the oneor more DAUs.

In some embodiments, the one or more DAUs may be coupled together via atleast one of Ethernet cable, Optical Fiber, Microwave Line of SightLink, Wireless Link, or Satellite Link. In some embodiments, theplurality of RDUs may be connected to the one or more DAUs via at leastone of Ethernet cable, Optical Fiber, Microwave Line of Sight Link,Wireless Link, or Satellite Link. In some embodiments, the plurality ofRDUs may be interconnected in a daisy chain configuration. In otherembodiments, the plurality of RDUs may be connected to one of the one ormore DAUs in a star configuration. In some embodiments, the plurality ofRDUs may include multi-frequency, multi-operator and multi-antennacharacteristics. In some embodiments, the plurality of RDUs may exhibitmultiple input multiple output (MIMO) characteristics.

Some embodiments may include a method for routing signals in aDistributed Antenna System (DAS). The method may comprise receiving at arepeater digital unit (RDU) a radio frequency (RF) signal from a remotebase transceiver station (BTS), converting the signal from RF to adigital signal, and transporting the digital signal through an opticalcable to a digital access unit (DAU). Embodiments may also includemultiplexing the digital signal, and routing the multiplexed signal fromthe DAU to at least one digital remote unit (DRU). Some embodiments mayalso include demultiplexing the digital signal at the least one DRU toregenerate the digital signal. In some embodiments, the RDU may compriseone or more PEER ports and one or more LAN ports. In some embodiments,the DAU may comprise one or more PEER ports and one or more LAN ports.

Numerous benefits are achieved by way of the present invention overconventional techniques. Traditionally an Off-Air Repeater communicateswith the donor BTS via a wireless RF signal and communicates with thecoverage area via a wireless RF signal. Off-Air Repeaters are prone toinstability because of their high gain and RF coupling between the DonorRF port and the Coverage RF port. A software configurable digitalrepeater digital unit (RDU) relays the RF signals to a DAU via anoptical cable. The RF signals from the Off-Air Repeater are transporteddigitally over an optical cable to one or more DAUs. This eliminates theinstability problems associated with a traditional Off-Air Repeater aswell as enabling multiple Off-Air Repeaters to be configured in a staror daisy chain configuration. Transporting the Off-Air Repeater signalfrom the donor BTSs optically provides an additional benefit of enablingmultiplexing of multiband signals from multiple Off-Air Repeaters.Additionally, embodiments enable the routing of the Off-Air Repeatersignals to one or more remote locations. These and other embodiments ofthe invention along with many of its advantages and features aredescribed in more detail in conjunction with the text below and attachedfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram according to one embodiment showing a basicstructure and an example of the transport routing based on having athree-sector BTS with 3 Digital Access Units (DAUs) at a local location,two Repeater Digital Units (RDUs) at a local location and Digital RemoteUnits (DRUs) at a remote location. In embodiments according to FIG. 1,two RDUs are connected to a DAU at the local location.

FIG. 2A is a block diagram according to one embodiment showing a basicstructure and an example of the transport routing based on having athree-sector BTS with 3 DAUs at a local location, two RDUs daisy chainedtogether at a local location and optical interfaces to DRUs at theremote locations.

FIG. 2B is a timing diagram reflecting the framing of the multiplefrequency bands for the uplink and downlink signals according to someembodiments.

FIG. 3 is a block diagram according to some embodiments showing a basicstructure and an example of the transport routing based on havingmultiple RDUs at local locations with multiple DAUs at a local location,and multiple Digital Remote Units (DRUs) at a remote location andoptical interfaces to the Remotes.

FIG. 4 is a block diagram illustrating a DAU, which contains physicalNodes and a Local Router, according to some embodiments.

FIG. 5 is a block diagram illustrating a Repeater Digital Unit (RDU),which contains physical Nodes and a repeater router, according to someembodiments.

FIG. 6 illustrates an example flowchart according to some embodiments.

FIG. 7 is an illustration of multiple input-multiple output (MIMO)configurations, according to some embodiments.

FIG. 8 is a block diagram according to some embodiments showing a basicstructure and an example of the transport routing based on havingmultiple MIMO (multiple input-multiple output) RDUs at local locationswith multiple DAUs at a local location, and multiple Digital RemoteUnits (DRUs) at a remote location and optical interfaces to the Remotes.

DETAILED DESCRIPTION

Embodiments may be drawn to off air repeaters, which aretelecommunications repeaters that take a signal “off air,” but “over theair.” Traditionally, repeaters in the prior art may be coupled to basetransceiver stations (BTS) via radio frequency (RF) cable. Typically,all communications to and from repeaters in the prior art may occur viaRF. There may be several problems to the traditional approach ofrepeaters. One problem may be that feedback may occur from the RF cableconnecting the repeaters to the antenna at the BTS. This feedback maycause signal oscillations, which results in co-channel interference.Another problem may be that the quality of the signal may degrade overlonger distances of RF cable, due to cable losses over longer distances.

In addition, in traditional configurations having a base station in anenclosed, less accessible area, e.g. a basement, only sometelecommunications operators—e.g. AT&T, Verizon, etc.—may own basestations in that enclosed area. Other operators, e.g. Sprint orT-Mobile, may not own base stations housed in that same area, butinstead may own base stations that are at some remote location, e.g.locations 2 kilometers away. Users near the basement—e.g. users in thesame building above the basement—with subscriptions to AT&T and Verizonshould have superior reception compared to users near the basement withsubscriptions to Sprint or T-Mobile. It may be desirable then foroperators of remote base stations to be able to access the base stationsin the basement, rather than build their own base stations and spendmore resources in the process. It may also be desirable to transmitsignals from the remote BTSs to the local source in a reliable andefficient manner, without loss of signal quality and minimalinterference.

An off air repeater according to embodiments may help solve at leastthese problems. Embodiments may allow remote BTSs physically locatedaway from a local source of users to be able to provide local service asif the remote BTSs were at or near the local source of users. In someembodiments, base stations may be housed in areas that are lessaccessible, e.g. in a basement of a building. In this context, someembodiments may house a rack of digital access units (DAUs) close to thebase station which may be coupled via RF cable. Embodiments may utilizean off-air repeater, or a repeater digital unit (RDU), to route signalsfrom the remote BTSs over the air to at least one DAU (e.g. a rack ofDAUs) housed near the local source of users (e.g. the basement in thebuilding of the users). RDUs of some embodiments may receive theDownlink RF signal from a donor/remote BTS, amplify and filter the RFsignal and then re-transmit it to a coverage area. The coverage area maybe outdoors or indoors. The uplink signal from the coverage area may beamplified, filtered and re-transmitted to the donor/remote BTS. Atraditional repeater has one or more RF input ports and RF output ports.Using RF cables between the Repeater and indoor antennas facilitatesindoor coverage. Embodiments may utilize optical cable, instead of RF,connecting from the RDUs to the at least one DAU. The optical cablingmay allow for digital transmission of signals between the remote BTSsand the at least one DAU. Once signals reach the at least one DAU, theycan be routed to various digital remote units (DRUs), which may provideclose reception to the local source of users.

As previously mentioned, embodiments may utilize RDUs connected byoptical cabling, rather than RF cabling, to transport signals.Advantages may include, for example, eliminating co-channelinterference. Another may be having the ability to multiplex the RFsignal due to transporting the signal digitally. Another advantage maybe reducing or eliminating signal degradation due to transporting thesignal digitally. Also, embodiments may be distinguishable fromtraditional systems with repeaters in that the downlink and uplinksignal directions between RDUs and DRUs may be reversed. For example,signals coming from an RDU, going down to a DAU and then being routed toDRUs may traditionally be downlink signals. In contrast, embodimentshave the ability to reverse the direction of the downlink and uplinksignals in the DAU.

FIG. 1 may illustrate a distributed antenna system (DAS) networkarchitecture according to some embodiments of the present invention. ADAS according to some embodiments may provide an efficient means ofutilization of base station resources. The base station or base stationsassociated with a DAS can be located in a central location and/orfacility commonly known as a base station hotel. The DAS networkcomprises one or more digital access units (DAUs) that function as theinterface between the base stations and the digital remote units (DRUs).The DAUs can be collocated with the base stations. The DRUs can be daisychained together and/or placed in a star configuration and providecoverage for a given geographical area. The DRUs may be connected withthe DAUs by employing a high-speed optical fiber link. This approach mayfacilitate transport of the RF signals from the base stations to aremote location or area served by the DRUs. A base station may comprisethree independent radio resources, commonly known as sectors. Thesethree sectors may be used to cover three separate geographical areaswithout creating co-channel interference between users in the threedistinct sectors. In other embodiments, additional sectors areassociated with each BTS, for example, up to or more than twelvesectors.

Here, FIG. 1 provides an example of a data transport scenario between athree-sector Base Station, multiple local DAUs, multiple RepeaterDigital Units (RDUs) and multiple DRUs. BTS1 100 is connected to DAU1102, DAU2 108, and DAU3 111 (i.e., local DAUs) by an RF cable in theillustrated embodiment. BTS2 130 and BTS3 140 communicate Off-Air RFsignals with RDU1 120 and RDU2 121, respectively. Each of the local DAUsis connected to server 150. In FIG. 1, the RDUs are connected in a starconfiguration with DAU1 102 using optical cables. The followingdescriptions provide additional detail to several different features inFIG. 1 according to some embodiments.

Still referring to FIG. 1, multiple RDUs, e.g. RDU1 120 and RDU2 121,may be placed in varying locations while being connected to the sameDAU1 102. Each RDU may provide repeater service to a different BTS, e.g.RDU1 120 provides repeater service for BTS2 130 to DAU1 102, and RDU2121 provides repeater service for BTS3 to DAU1 102. Multiple RDUsservicing multiple remote BTSs may be beneficial for several reasons.For example, the DAUs 102, 108, 111. may be housed in a building, and atelecommunications operator, e.g. Sprint, may have a remote BTS locatedwest of the building, a few kilometers away. Thus, it would be desirableto have an antenna on the top of the building facing west. At the sametime, another telecommunications operator, e.g. T-Mobile, may have abase station that is north of the building. Thus, it would be beneficialto have two different repeaters communicating with those different basestations, one for the northern located BTS and the other for the westernlocated BTS. Other benefits may include an ability for multipletelecommunications operators to have more exclusive control and accesswith different RDUs. Other benefits may include reducing resourcesneeded to optimally service multiple operators.

Some embodiments include the ability to route the local Base Station 100and remote Base Stations 130, 140 radio resources, among the RDUs andDAUs. In order to route radio resources available from one or more BaseStations, it may be desirable to configure the individual router tablesof the DAUs and RDUs in the DAS network. This functionality may beprovided by some embodiments.

Still referring to FIG. 1, the DAUs may be networked together tofacilitate the routing of signals among multiple DAUs. The DAUs maysupport the transport of the RF downlink and RF uplink signals betweenthe BTSs and the various DAUs. This architecture may enable the variousBTS signals to be transported simultaneously to and from multiple DAUs.PEER ports are used for interconnecting DAUs. PEER ports may bediscussed in more detail in later paragraphs of this disclosure.

The DAUs may have the capability to control the gain (in smallincrements over a wide range) of the downlink and uplink signals thatare transported between the DAU and the base station (or base stations)connected to that DAU. This capability may provide flexibility tosimultaneously control the uplink and downlink connectivity of the pathbetween a particular RDU (or a group of RDUs) and a particular basestation.

The DAU may communicate with a Network Operational Control (NOC). TheNOC sends commands and receives information from the DAS network. TheDAS network can include a plurality of DAUs, RDUs and DRUs. The DAUcommunicates with the network of DRUs and the DAU sends commands andreceives information from the DRUs. The DAUs include physical nodes thataccept and deliver RF signals and optical nodes that transport data. ADAU can include an internal server or an external server. The server isused to archive information in a database, store the DAS networkconfiguration information, and perform various traffic relatedprocessing. The server can be used to communicate information from theDAS Network to the NOC.

Additionally, an RDU may communicate with a DAU or rack of DAUs. In someembodiments, the RDU does not communicate with the NOC. The RDU receivescommands from the DAU and delivers information to the DAU. The RDUsinclude physical nodes that accept and deliver RF signals and opticalnodes that transport data.

As previously mentioned, BTS1 100 may be separated into a plurality ofsectors. In this case, BTS1 100 shows three sectors: sector 1 101,sector 2 109, and sector 3 110. Each sector may be associated with atleast one antenna on top of at least one tower, each antenna connectedto typically an RF cable that would connect to BTS1 100. Each antennawould provide signal coverage up to some angle, e.g. 120 degrees, aroundBTS1 100. Thus, when combining all three sectors, BTS1 100 may provide360 degrees of signal coverage.

Each sector may be connected via RF cable to a DAU. In this case, sector1 101 is connected to DAU1 102, sector 2 109 is connected via RF cableto DAU2 108, and sector 3 110 is connected via RF cable to DAU3 111. Inother embodiments, the sectors may be connected to the same DAU. In someembodiments, each DAU may be owned by a different telecommunicationsoperator, allowing each operator to control information of itssubscribers. Each DAU may also contain a neutral host that allows otheroperators to transmit their information and signals to DAUs they do notcontrol.

As alluded to above, embodiments may allow for differenttelecommunications operators with remote base stations to providestronger signal coverage to a local building containing the DASarchitecture according to some embodiments described herein. Forexample, say Verizon owns BTS2 130, and T-Mobile owns BTS3 140, butMetro PCS owns BTS1 100 and Verizon and T-Mobile do not normally haveaccess to BTS1 100. However, both Verizon and T-Mobile want coverage inthe building housing BTS1 100. Transmitting signals just from theirrespective BTSs 130, 140, Verizon and T-Mobile may be able to provideonly weak signal coverage to the building because the building isseveral kilometers from their respective BTSs 130, 140. Using variousembodiments of the present invention, however, the RDUs connecting theBTSs 130, 140 may allow Verizon and T-Mobile to provide coverage to thebuilding with a signal strength just as strong as Metro PCS.

Embodiments may connect the DAUs to various cells of DRUs to completethe configuration of supplying signals of different operators fromremote BTSs to their customers or users. In this case, cell 1 105, cell2 106, and cell 3 107 may contain a “flower” arrangement of DRUs, whichmay be located in the building. Thus, each operator may provide strongcoverage to all of the users that cell 1 105, cell 2 106, and cell 3 107provide coverage for, even though some other operator's BTSs are locatedfar away.

In FIG. 1, server 150 is shown to be connected to the three DAUs 102,108, and 111. In some embodiments, a server 150 may provision all theDRUs, all the DAUs and the RDUs to be configured as needed. In essence,server 150 may act like a network management server. In otherembodiments, server 150 may configure how the DAS is going to be set up.Each DAU, DRU, and RDU may contain a series of ports that areconfigurable, depending on need and function. Server 150 may facilitatedesignation of what each port is supposed to function as. For example, aport may act as a PEER port, or a LAN port, and server 150 may designatethat. In another example, server 150 may configure the DRUs because someof the DRUs may only be able to transmit certain bands. An exampledescription of the hardware configurations will be described in laterfigures.

In addition, FIG. 1 may show a star configuration of RDUs, in that eachRDUs is connected to the same DAU1 102. In this case, signals indifferent frequency bands and with different frequencies within the samefrequency band may be summed in DAU1 102 to create a single compositesignal when transmitted to the various cells. The signals can then beseparated using traditional filtering techniques, knowing that thesignals each originate in different frequencies. A benefit to having astar configuration of RDUs may be where the BTSs are located ifdifferent geographic locations.

Referring to FIG. 2A, the individual base station radio resources fromBTS2 230, BTS3 231 and BTS4 232 are transported to a daisy-chainednetwork of RDUs. Each individual BTS radio resources provide coverage toan independent geographical area. FIG. 2A demonstrates how threeindependent BTSs, each BTS communicating with an independent RDU,provide input into a single DAU while the RDUs are connected in adaisy-chained configuration. A server 240 may be utilized to control therouting function provided in the DAS network, and may function similarlyto server 150 described in FIG. 1.

Referring to FIG. 2A and by way of example, DAU1 202 may receivedownlink signals and may transmit uplink signals from and to the daisychained network of RDUs 220, 221, 222. RDU1 220 may translate the RFsignals to optical signals for the downlink and may translate theoptical signals to RF signals for the uplink. The optical fiber cable224 may transport the BTS2 230 signals between RDU1 221 and RDU2 222.The optical signals from RDU1 221 and RDU2 222 may be multiplexed onoptical fiber cable 225. The other RDUs in the daisy chain may beinvolved in passing the optical signals onward to DAU1 202. DAU1 202,DAU2 208 and DAU3 211 may transport the optical signals to and from thenetwork of DRUs, at cells 1 205, 2 206, and 3 207.

Benefits of daisy chaining RDUs according to some embodiments mayinclude connecting multiple RDUs in near proximity to each other withminimal cabling. In addition, another RDU may be easily connected in thedaisy chain with minimal cabling.

An RDU communicates over the air with a base station (BTS). The basestation is generally specific to a given operator. The RDU is requiredto frequency select via a digital filter the band allocated to thatgiven operator and reject signals from other operators. This approach isrequired to insure that another operator's signal is not transported tothe venue. The RDU will contain a digital bandpass filter for thereceive as well as the transmit paths. The installer will select thedigital bandpass filters.

Referring to FIG. 2B, timing schematics 250 and 251 show example timingdiagrams for different frequency bands for the uplink signals anddownlink signals. Each frequency band is allocated a time slot and thesignals are time multiplexed together. The same principles may hold truefor the upstream frames shown in timing schematic 251. These principlesmay be consistent with the multiplexing examples described in any of thedisclosures herein. The time divisions may be of any evenly dividedlengths, and embodiments are not so limited.

Referring to FIG. 3, a DAS system employing multiple Repeater DigitalUnits (RDUs) at the local location and multiple Digital Remote Units(DRUs) at the remote location may be depicted according to someembodiments. In some embodiments, each RDU may provide uniqueinformation associated with each RDU, which uniquely identifies datareceived and transmitted by a particular Digital Remote Unit. In someembodiments consistent with FIG. 3, the individual RDUs may beindependently connected to DAUs. FIG. 3 may show how some embodimentsmay have separate RDUs connected directly to a separate DAU, in neithera daisy chain or a star configuration. Such embodiments may be usefulwhen operators desire their own separate connection from their BTS tothe subscribers within the DRU cells, e.g. cell 1 305, cell 2 306, orcell 3 307.

The servers illustrated herein, for example, server 350, may provideunique functionality in the systems described herein. The followingdiscussion related to server 350 may also be applicable to other serversdiscussed herein an illustrated in the figures. Server 350 can be usedto set up the switching matrices to allow the routing of signals betweenthe remote DRUs. The server 350 can also store configurationinformation, for example, if the system gets powered down or one DRU orRDU goes off-line and then you power up the system, it will typicallyneed to be reconfigured. The server 350 can store the information usedin reconfiguring the system and/or the DRUs, RDUs or DAUs.

Another advantage of embodiments according to FIG. 3 may be that allsignals occur off air. In other words, there is no BTSs connected via RFcable. For example, an operator like AT&T may not want to share anythingwith another operator, like Verizon. Each operator may want their ownequipment. With their own equipment, each operator may control the powerlevels and other configurable parameters.

While each operator may have their own equipment according to FIG. 3,there may still be value in connecting each DAU to each other, alsoshown in FIG. 3. For example, routing signals from one DAU to anothermay still be desired. This may be because, for example, the DRU cells asshown in FIG. 3 may be connected via optical cable to only one of thethree DAUs. Each DRU cell may provide coverage to different geographicareas, and each operator may still desire to provide coverage to allthree areas. Thus, any or every BTS may still want to have access to thedifferent cells, which in this case may require a connection to eachDAU. In cases like these, a neutral host built into the DAUs may provideaccess from the different DAUs to the DRU cells without interfering witheach operator's own telecommunications operations. A neutral host mayitself be a repeater, not unlike the RDUs described in the presentdisclosures.

Thus, in some embodiments, the repeater concept familiar to those withordinary skill in the art may be redistributed into at least tworepeater elements, according embodiments consistent with FIG. 3. Personsof ordinary skill in the art may observe that RDU1 321 and DRU16together may act as a repeater in the traditional sense. This is becauseRF is coming into the RDUs, and RF is going out of the DRUs, which maybe what a traditional repeater may behave like. Of course, thebifurcation of the repeater concept may not be trivial or obviouswithout the present disclosures.

FIG. 4 may show two elements in a DAU, the Physical Nodes 400 and theLocal Router 401. The Physical Nodes translate the RF signals tobaseband for the Downlink and from baseband to RF for the Uplink. Thelocal Router directs the traffic between the various LAN Ports, PEERPorts and the External Ports. The physical nodes connect to the BTS atradio frequencies (RF). The physical nodes can be used for differentoperators, different frequency bands, different channels, or the like.The physical nodes can combine the downlink and uplink signals via aduplexer or they can keep them separate, as would be the case for asimplex configuration.

FIG. 4 may illustrate a digital access unit (DAU) according to someembodiments whereby the physical nodes have separate outputs for theuplinks 405 and separate inputs for the downlink paths 404. A DAUconsistent with FIG. 4 may serve as one of the DAUs found in any of FIG.1, 2, or 3. The physical node may translate the signals from RF tobaseband for the downlink path and from baseband to RF for the uplinkpath. The physical nodes are connected to a local Router via externalports 409, 410. The router may direct the uplink data stream from theLAN and PEER ports (e.g. LAN Port 1, LAN Port 2, PEER Port M, etc.) tothe selected External U ports. Similarly, the router directs thedownlink data stream from the External D ports to the selected LAN andPEER ports.

Embodiments may vary or reconfigure which ports 401 may be LAN or PEER.FIG. 4 is merely one example, and many other configurations are possibleaccording to embodiments of the present invention. DAUs of someembodiments may be reconfigurable in this sense in order to adapt to thevarious DAS configurations possible, examples of which may include FIGS.1, 2, and 3.

A difference between a LAN port and a PEER port may be that a LAN portwould have the downlink signal going out, and the uplink signal comingback. A PEER port would be the exact opposite. It would have thedownlink signal coming into the DAU, and the uplink signal going out ofit. Thus, when provisioning the DAU, for example, assume that there is arepeater RDU1 connected to PEER port M. If is it known there is arepeater there, then it may be understood that a PEER connection must beestablished. Thus, the port is designated as a PEER port. In contrast, aLAN port, e.g. LAN port 1, may connect up to the daisy chain of DRUs, asshown in FIGS. 1, 2, and 3.

As another example, PEER ports may provide the connection between DAU1102 and DAU2 108 of FIG. 1, which may be represented as the two-wayarrow between the DAUs 102 and 108 according to the figures. In anotherexample, PEER ports may be used to daisy chain the DAUs together.

Referring again to FIG. 4, in some embodiments, the LAN and PEER portsmay be connected via an optical fiber to a network of DAUs and DRUs. Thenetwork connection can also use copper interconnections such as CAT 5 or6 cabling, or other suitable interconnection equipment. The DAU is alsoconnected to the internet network using IP 406. An Ethernet connection408 is also used to communicate between the Host Unit 402 and the DAU.The DRU and RDU can also connect directly to the Remote OperationalControl center 407 via the Ethernet port. Again, these descriptions maybe consistent with the DAUs shown in FIGS. 1, 2, and 3.

FIG. 5 may show two elements in a repeater digital unit (RDU) accordingto some embodiments: the Physical Nodes 501 and the Repeater Router 500.The RDU may include both a Repeater Router and Physical Nodes. TheRepeater Router may direct the traffic between the LAN ports, ExternalPorts and PEER Ports. The physical nodes may connect wirelessly to theBTS at radio frequencies (RF). The physical nodes can be used fordifferent operators, different frequency bands, different channels,different antennas, etc. FIG. 5 shows an embodiment whereby the physicalnodes have separate inputs for the uplinks 504 and separate outputs forthe downlink paths 503. A physical node may translate signals from RF tobaseband for the uplink path and from baseband to RF for the downlinkpath. The physical nodes are connected to a Repeater Router via externalports 506, 507. The router may direct the downlink data stream from theLAN and PEER ports to the selected External D ports. Similarly, therouter directs the uplink data stream from the External U ports to theselected LAN and PEER ports. The RDU may also contain an Ethernet Switch505 so that a remote computer or wireless access points can connect tothe internet.

In some embodiments, the RDUs each have an amplifier to send out theuplink signal down to a BTS. For example, in FIG. 1, an amplifier inRDU1 120 may be included to send that signal out to BTS2 130. In DRU16,the amplifier is actually in the downlink path. Thus, structurally alarger amplifier on the different uplink for the repeater may be neededas opposed to the downlink for the DRU16. Thus, one difference to notebetween a RDU and a DRU may be that the uplink and downlink signals arereversed in a RDU compared to a DRU, and vice versa. That is, thedownlink signals come in to a DRU, while the downlink signals go out ofthe RDU.

In some embodiments, a RDU and a DAU may be constructed quite similarly,such that a single platform may easily switch from being configured as aRDU to a DAU. Such a construction may be another benefit according tosome embodiments, allowing for flexibility, cost efficiency, elegantdesign and ease of replacement, among other advantages.

In some embodiments, the DAU may be connected to a host unit/server,whereas the RDU may not connect to a host unit/server. In theseembodiments, parameter changes for the RDU may be received from a DAU,with the central unit that updates and reconfigures the RDU being partof the DAU, which can be connected to the host unit/server. Embodimentsof the present invention are not limited to these embodiments, which aredescribed only for explanatory purposes.

Referring to FIG. 6, example flowchart 600 shows example method stepsaccording to some embodiments. At block 610, embodiments may receive ata repeater digital unit (RDU) a radio frequency (RF) signal from aremote base transceiver station (BTS). Example processes of block 610may be consistent with any of the descriptions in FIGS. 1, 2, and 3related to receiving signals at any RDU described. Returning to FIG. 6,at block 612, embodiments may convert the signal from RF to a digitalsignal. The conversion may occur in the RDU, consistent withdescriptions in FIG. 5, for example. Returning to FIG. 6, signalprocessing of the digital signal will occur at block 613. The signalprocessing may include filtering, data compression, frequencytranslation, etc. At block 614, embodiments may transport the digitalsignal through an optical cable to a digital access unit (DAU). Again,FIGS. 1, 2, and 3 may show examples of this transportation. Returning toFIG. 6, block 616, embodiments may multiplex the digital signal.

Examples of multiplexing the digital signal may include combining two ormore signals that occur at different frequencies or frequency bands. Forexample, a first operator, e.g. AT&T may transmit a first signal via afirst BTS with a first frequency. A second operator, e.g. Verizon, maytransmit a second signal via a second BTS with a second frequencydifferent than the first. The two signals may be multiplexed such that asingle combined signal contains information sufficient to filter out thetwo original signals at a later time and place. These descriptions maybe consistent with those discussed in FIGS. 1, 2, and 3. In FIG. 6, atblock 618, embodiments may route the multiplexed signal from the DAU toat least one digital remote unit (DRU). The routing may be sent overoptical cable or Ethernet cable, for example. These descriptions may beconsistent with those found in FIGS. 1, 2, and 3.

Additionally, some embodiments may include that the RF signal from theremote base station has a downlink and an uplink. Some embodiments mayinclude that the RDU and/or the DAU has PEER ports and LAN ports. PEERports may be distinguished from LAN ports based on which path to andfrom the RDU and/or DAU is designated as a downlink path versus anuplink path.

FIG. 7 is an illustration 700 of a multiple input-multiple output (MIMO)configuration. The number of transmit (Tx) antennas and receive (Rx)antennas will determine the classification of the system. MIMO systemscan be expanded to N Transmit antennas and M Receive antennas, where Nand M are integers greater than one.

FIG. 8 demonstrates the application of a MIMO repeater, RDU1 820,according to some embodiments. Also shown is another MIMO repeater RDU2821. A MIMO repeater according to some embodiments interfaces with a DAUbefore the signal is transported out to the remote units. The MIMO RDUscan be cascaded together at the DAU as shown in FIG. 8 or they could bedaisy-chained together. Each antenna in a MIMO RDU may be treated as aseparate frequency band, and thus MIMO signals transmitted to andreceived from the DAU, e.g. DAU1 802, may be similarly time divisionmultiplexed, as described in the disclosures above. For example, extratime slots for the signals from the additional antennas may be providedas information travels through the optical cables 823 and 824. In someembodiments, no other configurations need to be modified in comparisonto non-MIMO RDUs.

It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this applicationand scope of the appended claims.

GLOSSARY OF TERMS

-   ACLR Adjacent Channel Leakage Ratio-   ACPR Adjacent Channel Power Ratio-   ADC Analog to Digital Converter-   AQDM Analog Quadrature Demodulator-   AQM Analog Quadrature Modulator-   AQDMC Analog Quadrature Demodulator Corrector-   AQMC Analog Quadrature Modulator Corrector-   BPF Bandpass Filter-   BTS Base Transceiver Station-   CDMA Code Division Multiple Access-   CFR Crest Factor Reduction-   DAC Digital to Analog Converter-   DAS Distributed Antenna System-   DAU Digital Access Unit-   DET Detector-   DHMPA Digital Hybrid Mode Power Amplifier-   DDC Digital Down Converter-   DNC Down Converter-   DPA Doherty Power Amplifier-   DQDM Digital Quadrature Demodulator-   DQM Digital Quadrature Modulator-   DRU Digital Remote Unit-   DSP Digital Signal Processing-   DUC Digital Up Converter-   EER Envelope Elimination and Restoration-   EF Envelope Following-   ET Envelope Tracking-   EVM Error Vector Magnitude-   FFLPA Feedforward Linear Power Amplifier-   FIR Finite Impulse Response-   FPGA Field-Programmable Gate Array-   GSM Global System for Mobile communications-   I-Q In-phase/Quadrature-   IF Intermediate Frequency-   LINC Linear Amplification using Nonlinear Components-   LO Local Oscillator-   LPF Low Pass Filter-   MCPA Multi-Carrier Power Amplifier-   MDS Multi-Directional Search-   MIMO Multiple Input Multiple Output-   OFDM Orthogonal Frequency Division Multiplexing-   PA Power Amplifier-   PAPR Peak-to-Average Power Ratio-   PD Digital Baseband Predistortion-   PLL Phase Locked Loop-   QAM Quadrature Amplitude Modulation-   QPSK Quadrature Phase Shift Keying-   RF Radio Frequency-   RDU Repeater Digital Unit-   RRH Remote Radio Head-   RRU Remote Radio Head Unit-   SAW Surface Acoustic Wave Filter-   UMTS Universal Mobile Telecommunications System-   UPC Up Converter-   WCDMA Wideband Code Division Multiple Access-   WLAN Wireless Local Area Network

1. (canceled)
 2. A digital unit in a distributed antenna system (DAS),the digital unit comprising: a radio frequency (RF) port operable tocommunicate with a base tranceiver station (BTS); a converter operableto convert communications to and from the BTS between analog signals anddigital signals; and an optical port operable to route the digitalsignals to one or more remote units.
 3. The digital unit of claim 1,wherein the RF port is operable to communicate with the base transceiverstation via an antenna.
 4. The digital unit of claim 1, wherein the RFport is operable to communicate with the BTS via a cable.
 5. The digitalunit of claim 1, wherein the BTS is located remotely from the digitalunit.
 6. The digital unit of claim 1, wherein the RF port is operable tocommunicate with a sector of the BTS.
 7. The digital unit of claim 1,further comprising: an access unit; and a repeater.
 8. The digital unitof claim 7, wherein the access unit is coupled to the repeater unit viaan optical fiber.
 9. The digital unit of claim 7, wherein the accessunit is operable to exchange digital signals with the repeater.
 10. Thedigital unit of claim 7, wherein the access unit is operable to routecommunications between the repeater and at least one of the one or moreremote units.
 11. The digital unit of claim 1, wherein the one or moreremote units are located at different locations than the digital unit.12. The digital unit of claim 1, wherein the digital unit is operable toroute the digital signals to another digital unit.
 13. The digital unitof claim 1, wherein the digital unit is operable to route the digitalsignals to another BTS.
 14. A system comprising: a digital unit, thedigital unit configured to: communicate with at least one basetransceiver station (BTS); convert communications to and from the atleast one BTS between analog and digital; route digital signals from thedigital unit to another digital unit; and route digital signals betweenthe at least one BTS and at least one remote unit.
 15. The system ofclaim 14, wherein the digital unit is operable to communicate with theat least one BTS via at least one of an antenna or a cable.
 16. Thesystem of claim 14, wherein the at least one BTS is located remotelyfrom the digital unit.
 17. The system of claim 14, wherein the digitalunit is operable to communicate with a sector of the BTS.
 18. The systemof claim 14, wherein the digital unit includes: an access unit; and arepeater.
 19. The system of claim 18, wherein the access unit is coupledto the repeater unit via an optical fiber.
 20. The system of claim 18,wherein the access unit is operable to exchange digital signals with therepeater.
 21. The system of claim 14, wherein the digital unit isoperable to route the digital signals to another digital unit.